This invention relates to fiber optics, and, more specifically, to control modules for fiber optic control systems and a fiber optic control system for an apparatus.
Purely electrical controls for apparatus such as machine tools, packaging equipment, or the like, are limited in application due to a variety of factors. In many instances, where the equipment is operated in a potentially explosive atmosphere, electrical controls cannot be employed due to the possibility of electrical arcing at switch contacts igniting the surrounding atmosphere. Other difficulties attend the use of electrical controls in many environments. For example, due to building codes, wires employed in electrical controls must be housed in conduits and thus installation expenses can become quite high. In other instances, deterioration of contacts may require significant maintenance and/or cause excessive down time. In addition, many electrical components used in control circuits as, for example, relays, are quite expensive.
Troubleshooting of electrical circuits is often difficult due to the need for specialized equipment used for testing purposes.
As a consequence, there is an increasing rate of use of other types of control systems as, for example, pneumatic control systems utilizing miniaturized valves. Such air control systems possess significant advantages over electrical systems in terms of ease of maintenance, lesser initial expense, ability to operate in hazardous environments, etc. Moreover, because many such systems employed today allow interconnection of the various components with flexible plastic tubing, installation expense is minimal.
However, because such systems utilize interengaging, movable, mechanical parts, as valves and valve seats, they are subject to wear and ultimate failure, thereby requiring some maintenance and causing some down time.
Moreover, because such systems employ compressed air, their reliability is, to some extent, dependent upon the user's following a good maintenance procedure with his source of compressed air so that only clean compressed air is provided to the system components. Therefore, some preventive maintenance is required even with air systems.
Thus, there is a real need for a control system that retains all the advantages of known air systems over electrical systems and yet further minimizes such maintenance difficulties as are associated therewith.